During the assembling of a direct current motor, an operator aligns long screw through holes of a front end cover, a housing and a rear end cover by marking or by providing a structure having small recesses or bumps on the housing, and then, compressing and thus fixing the front end cover, the housing and the rear end cover by hands to introduce a long screw. Because a corrugated gasket is provided between the housing and the front end cover and between the housing and the rear end cover, it is unable to firmly fix the front end cover, the housing and the rear end cover manually. As a result, several attempts of screwing a long screw is required to complete the assembly of the front end cover, the housing and the rear end cover of a direct current motor. This increases the labor intensity of the operators and decreases the operating efficiency.